The semiconductor integrated circuit (IC) industry has experienced rapid growth. During the growth, size or geometry of semiconductor devices has greatly decreased. Moreover, in order to promote the performance of semiconductor devices, the placement of decoupling capacitors (DECAPs) is a common approach to reduce the power supply noises and voltage fluctuations and maintain power and signal integrity. Generally, the decoupling capacitor is used in many integrated circuits such as complementary metal-oxide semiconductor (CMOS).
However, because the voltages provided by different power supplies vary within wide limits, it is difficult to implement sufficient decoupling capacitors for all types of power supplies. Specifically, the power supplies providing high voltages are usually in need of the decoupling capacitors with high capacitance to reduce noises. Generally, decoupling capacitors with high capacitance usually require a large amount of installation space that makes it difficult to find space in small-size semiconductor devices to provide enough decoupling capacitors for each power supply. Accordingly, a semiconductor structure including an improved capacitor structure with high capacitance at a small size and a fabricating method of the semiconductor structure are required.